Various types of positive interlocks have been proposed and examples of two types that are presently being used commercially are disclosed in U.S. Pat. Nos. 3,811,582 and 3,921,835, both assigned to the assignee of the present invention. While both types of interlocks disclosed in the respective patents have been successful and been accepted in the industry, manufacturers are constantly striving for new features which can be incorporated into the vehicle at a minimum cost.